In metallurgy, it is known to wind and unwind metal strips on expandable mandrels. During unwinding and winding, the mandrel is expanded, whereas it must be shrunk to allow easy placement of the coil in the unwinder or easy removal of the coil from the winder.
To avoid marking inner turns of the coil during winding, an elastic sleeve is generally placed on the mandrel. Such sleeves are described in documents JP 2008229707, JP 2005014091 and JP 11057853.
The elastic sleeve must be able to follow the movements of the mandrel while remaining rigidly secured thereto when the coil is removed from the mandrel. To that end, it is common practice to provide a retaining device for the elastic sleeve. This device must prevent the elastic sleeve from being removed from the mandrel with the coil. This device is typically fastened by screws or other similar means. Thus, in document JP 2000000613, the retaining device is fastened using quarter-turn screws.
The elastic sleeves have a limited lifetime and must consequently be replaced periodically. It is also necessary to change the sleeve when the diameter of the eye of the coil varies.
Before the sleeve is removed, the mandrel must be fully retracted. The operator must stand in front of the mandrel, unscrew the retaining device and remove it. This operation is dangerous, since many machines work automatically in this location. It is then necessary for the operator to electrically, hydraulically, mechanically and pneumatically log the machines around the mandrel during the assembly and disassembly of the retaining device for the elastic sleeve. Then and only then, the sleeve can be disassembled and a new sleeve can be inserted on the mandrel with the necessary equipment for that unlogged operation. After the sleeve is placed, the operator must once again fasten the retaining device and, consequently, once again log all the machines in the surrounding area. All of these operations result in considerable lost time, which will be even greater if a handling machine for removing and placing the sleeve on the mandrel is also installed.